Renderotica

You are using texture shaded on the view port, while you are rendering in Iray.

All the view port options, save for filament or Iray Preview, are going to rely on OpenGL a hardware renderer so it is limited by what hardware your computer has. (Filament is a realtime render engine so it will show as it would render, and Iray Preview is basically handing things off to the Iray render engine so it updates in the view port, but unless you have Nvidia based GPU it is slow to update) and then after you press the render button it hands the scene off to the Software Render Engine (Iray or 3Delight) which then uses the CPU or GPU depending on system specs to calculate and render the final image.

So unless you're using Iray Preview, you'll never get a direct What You See is What You Get from the preview/view screen to render. And often how things interact in OpenGL is vastly different than how they'll act once handed off to the software render engines (And to make it more fun, how the two software render engines work is vastly different)